1. Field of the Invention
The present invention relates to a solar-shading light-transmissive panel with a multi-layer film including an Ag-rich layer comprising Ag as a main component, and a solar-shading multi-layer light-transmissive panel which employs such a solar-shading light-transmissive panel.
2. Description of the Related Art
In recent years, multi-layer window glass panes have been in widespread use to meet demands for highly hermetic, heat-insulated residential houses. For the purposes of increasing heat-insulating and solar-shading capabilities, there have also been widely used multi-layer glass panels with a multi-layer film including an Ag-rich layer comprising Ag as a main component. If a multi-layer glass panel with a multi-layer film including an Ag-rich layer is used as a window glass pane, then the window with such a window glass pane has increased heat-insulating and solar-shading capabilities. The heat-insulating capability is effective to cut down on the cost of heating the room in winter, and the solar-shading capability makes it possible to reduce the cost of air-conditioning the room in summer.
One conventional glass panel with a multi-layer film including an Ag-rich layer is disclosed in Japanese patent publication No. 7-15143, for example. As shown in FIG. 1 of the accompanying drawings, the disclosed glass panel comprises a transparent glass sheet 11, a first transparent dielectric layer 13, an Ag-rich layer 15, and a second transparent dielectric layer 17. The three layers 13, 15 and 17 are disposed successively on the sheet 11. The three layers 13, 15, 17 jointly make up a multi-layer film which will be referred to as xe2x80x9csingle-Ag LowExe2x80x9d.
Another conventional glass panel with a multilayer film including an Ag-rich layer is disclosed in Japanese laid-open patent publication No. 7-165442. As shown in FIG. 2 of the accompanying drawings, the disclosed glass panel comprises a transparent glass sheet 11, a first transparent dielectric layer 13, a first Ag-rich film 15, a second transparent dielectric layer 17, a second Ag-rich layer 19, and a third transparent dielectric layer 21. The five layers 13, 15, 17, 19 and 21 are disposed successively on the glass sheet 11. The five layers 13, 15, 17, 19, 21 jointly make up a multi-layer film which will be referred to as xe2x80x9cdouble-Ag LowExe2x80x9d.
Japanese laid-open patent publication No. 7-149545 discloses still another conventional glass panel with a multi-layer film including an Ag-rich layer. AS shown in FIG. 3 of the accompanying drawings, the disclosed glass panel comprises a transparent glass sheet 11, a first transparent dielectric layer 13, a first Ag-rich layer 15, a second transparent dielectric layer 17, a second Ag-rich layer 19, a third transparent dielectric layer 21, a third Ag-rich layer 23, and a fourth transparent dielectric layer 25. The seven layers 13, 15, 17, 19, 21, 23 and 25 are disposed successively on the transparent glass sheet 11. The seven layers 13, 15, 17, 19, 21, 23, 25 jointly make up a multi-layer film which will be referred to as xe2x80x9ctriple-Ag LowExe2x80x9d.
A comparison of the double-Ag LowE and the single-Ag LowE which have the same visible light transmittance indicates that the double-Ag LowE has a better solar-shading capability. Therefore, a multi-layer glass panel with the double-Ag LowE, which is used as a window glass pane, is more effective to suppress an indoor temperature rise due to solar radiation than, but introduces as much indoor light during daytime as, a multi-layer glass panel with the single-Ag LowE, which is used as a window glass pane.
A comparison of the triple-Ag LowE and the double-Ag LowE which have the same visible light transmittance reveals that the triple-Ag LowE has a better solar-shading capability. Therefore, a multi-layer glass panel with the triple-Ag LowE, which is used as a window glass pane, is more effective to suppress an indoor temperature rise due to solar radiation and hence to reduce an air-conditioning load than a multi-layer glass panel with the Double-Ag LowE, which is used as a window glass pane, while keeping a desired level of indoor light during daytime.
However, the double-Ag LowE is more costly than the single-Ag LowE to produce the films because the double-Ag LowE has more layers than the single-Ag LowE. Similarly, the triple-Ag LowE is more costly than the double-Ag LowE to produce the films because the triple-Ag LowE has more layers than the double-Ag LowE.
Office buildings find it most desirable to reduce an air-conditioning load from an energy saving viewpoint. For reducing the air-conditioning load on office buildings, solar-reflecting glass panels comprising one or more layers of metal oxide, metal, or metal nitride disposed on a transparent glass sheet are widely used as window glass panes for such office buildings. The conventional solar-reflecting glass panels are highly effective in reducing the air-conditioning load because they have as high a solar-shading ability as the triple-Ag LowE.
The solar-shading capabilities of glass panels with the single-Ag LowE and the double-Ag LowE are lower than the solar-shading capability of the conventional solar-reflecting glass panels. For this reason, indoor temperature increases due to solar radiation through office building window glass panes which comprise multilayer glass panels with the single-Ag LowE and the double-Ag LowE are greater than those through office building window glass panes which comprise conventional solar-reflecting glass panels. Consequently, it is preferable to use solar-reflecting glass panels as window glass =panes in terms of the solar-shading capability.
However, the visible light transmittance of solar-reflecting glass panels is much smaller than the visible light transmittance of the glass panels with the single-Ag LowE, the double-Ag LowE, or the triple-Ag LowE. If solar-reflecting glass panels are used as window glass panes, therefore, the rooms with those window glass panes are relatively dark during daytime, and the window glass panes give an unnatural impression to occupants in the rooms.
There has been known a solar-reflecting glass panel whose visible light transmittance has been increased by reducing the thickness of a metal or metal oxide film thereof for solving the above problem. However, the solar-reflecting glass panel with its visible light transmittance thus increased naturally has a reduced solar-shading capability. The solar-shading capability of a glass panel with the triple-Ag LowE is substantially the same as the solar-shading capability of a conventional solar-reflecting glass panel. However, such glass panel with the triple-Ag LowE is highly expensive to manufacture because the triple-Ag LowE is made up of seven layers.
It is therefore an object of the present invention to provide a solar-shading glass panel having a higher visible light transmittance than that of a conventional solar-reflecting glass panel and a solar-shading capability substantially equivalent to that of a glass panel with the double-Ag LowE or a conventional solar-reflecting glass panel.
Another object of the present invention is to provide a solar-shading glass panel which basically has four layers and hence can be manufactured relatively inexpensively.
According to the present invention, a solar-shading light-transmissive panel has a light-transmissive sheet, an absorbing layer disposed on said light-transmissive sheet, a first transparent dielectric layer disposed on said absorbing layer, an Ag-rich layer comprising Ag as a main component disposed on said first transparent dielectric layer, and a second transparent dielectric film disposed on said Ag-rich layer.
The light-transmissive sheet may be a glass sheet which is transparent or semitransparent in at least a visible light range or a synthetic resin sheet which is transparent or semitransparent in at least a visible light range. The glass sheet may be made of float glass, soda lime glass, borosilicate glass, crystallized glass, or the like. The synthetic resin sheet may be made of PET (polyethylene terephthalate), PVB (polyvinyl butyral), EVA (ethylvinyl acetate), cellulosic resin, or the like. Generally, the light-transmissive sheet has a thickness ranging from 1 to 15 mm, preferably from 2 to 10 mm.
The absorbing layer is capable of absorbing solar radiation rays to a certain extent. The absorbing layer has a visible light transmittance preferably in the range from 45 to 80%, and more preferably in the range from 50 to 75%. The absorbing layer may comprise a film of metal nitride having a thickness ranging from 1 to 20 nm, preferably from 2 to 15 nm, or a film of metal (metal or alloy) having a thickness ranging from 0.2 to 4 nm, preferably from 0.3 to 3.5 nm. The metal nitride may comprise at least one material selected from the group consisting of titanium nitride, zirconium nitride, tantalum nitride, and chromium nitride. If the absorbing layer is made of metal nitride, then the reflected color of an uncoated surface of the solar-shading light-transmissive panel has highly excellent repetitive reproducibility, and the reflected colors of both uncoated and coated surfaces of the solar-shading light-transmissive panel may easily be adjusted to natural colors. The metal may comprise at least one material selected from the group consisting of chromium, an alloy comprising mainly nickel and chromium, stainless steel, an alloy comprising mainly stainless steel, zinc, niobium, titanium, tantalum, zirconium, and tungsten.
Each of the first transparent dielectric layer, i.e., the first transparent dielectric layer, and the second transparent dielectric layer may comprise a single-layer made of at least one material selected from the group consisting of silicon nitride, titanium oxide, tin oxide, zinc oxide, zinc oxide doped with Al, and tin oxide doped with at least one of Sb and F, or multiple sub-layers comprising a plurality of layers each made of at least one material selected from the above group. These layers may be made of materials different from each other or some of these layers may be made of one material.
The Ag-rich layer may be made of Ag alone, or may be made of Ag to which there is added preferably 0.1 to 5%, more preferably 0.1 to 4%, of at least one material selected from the group consisting of Pd, Au, In, An, and Sn. The thickness of the Ag-rich layer is preferably in the range from 5 to 20 nm, and more preferably in the range from 7 to 17 nm.
A protective layer made of titanium oxide, silicon nitride, or the like and having a thickness ranging preferably from 5 to 30 nm, more preferably from 10 to 20 nm may be disposed on a surface of the second transparent dielectric film remote from the Ag-rich layer.
The solar-shading light-transmissive panel may also have an additional layer disposed on one or both surfaces of the Ag-rich layer, the additional layer being made of at least one material selected from the group consisting of titanium, chromium, an alloy comprising mainly nickel and chromium, stainless steel, an alloy comprising mainly stainless steel, zinc, niobium, tantalum, zirconium, and tungsten. The additional layer is effective to increase the heat resistance of the Ag-rich film, and also to prevent the Ag-rich layer from being oxidized when a transparent dielectric layer is formed on the Ag-rich layer in an atmosphere containing oxygen. Therefore, the Ag-rich layer is effectively prevented from being peeled off due to corrosion by the additional layer. The thickness of the additional layer is preferably in the range from 1 to 5 nm, and more preferably in the range from 1.2 to 4 nm.
The solar-shading light-transmissive panel has a visible light transmittance ranging preferably from 50 to 75%, and more preferably from 60 to 75%, and a solar transmittance ranging preferably from 20 to 45%, and more preferably from 20 to 40%. In order for the color of reflected light or transmitted light to look as natural as possible, the first transparent dielectric layer has a thickness ranging from 5 to 90 nm, preferably from 10 to 70 nm, and the second transparent dielectric layer has a thickness ranging from 10 to 90 nm, preferably from 15 to 70 nm.
According to the present invention, there is also provided a solar-shading double-layer light-transmissive panel, comprising the above solar-shading light-transmissive panel and at least one second light-transmissive sheet disposed in confronting relationship to the solar-shading light-transmissive panel, the solar-shading light-transmissive panel and the at least one second light-transmissive sheet being fixed relatively to each other such that the absorbing layer, the first transparent dielectric layer, the Ag-rich layer, and the second transparent dielectric layer are interposed between the light-transmissive sheet of the solar-shading light-transmissive panel and the at least one second light-transmissive sheet. The second light-transmissive sheet may be of the same material and thickness as those of the light-transmissive sheet of the above solar-shading light-transmissive panel. A second multi-layer film, which is the same as that of the light-transmissive sheet of the above solar-shading light-transmissive panel, may be disposed on the second light-transmissive sheet. The second multi-layer film should preferably be disposed between the second light-transmissive sheet on which the second multi-layer film is formed, and the light-transmissive sheet of the above solar-shading light-transmissive panel or another second light-transmissive sheet.
The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the resent invention by way of example.